Blogging is an excellent and cost effective (FREE) way to get your expertise out to the public. Sharing information about what you do, offer some day to day observations based on your profession on major blogging sites should cause community participation.
When blogging, imagine that you are a performer and you are trying to captivate the audience. Normally performers strive for applause or some other sort of positive feedback. As a blogger your applause or feedback is the comments you get. Unfortunately getting a comment on your privately hosted blog is a lot harder than getting one on a community blog site. This is because people on a sites such as Blogger, Typepad, Digg, StumbleUpon, Furl, FaceBook and Del.icio.us know how important it is to leave comments.
They know that by leaving comments on other peoples posts, they will get comments in return. That is why you as a blogger should always try to leave constructive comments on blogs that you happen to visit. This will not only give you a link back to your blog (a good SEO tactic) but may well invite a comment on your blog in return.
Also knowing how important it is to get comments, one should try, where possible, to phrase the blog in such a manner that it simply invites people to say something in reply.